Gursikhs can never lose a battle because both fateh and Gursikhs belong to Vaheguru. Siri Guru jee on ang 1356 of Siri Guru Granth Sahib jee has written briefly on a battle that takes place between Bhagats and the Bikaars. These bikaars that number 5 in count, are so strong that the whole world is under their control. Siri Guru jee starts the shabad by declaring that the army of Sant Gursikhs is unbeatable - ਸੈਨਾ ਸਾਧ ਸਮੂਹ ਸੂਰ ਅਜਿਤੰ ...|| The army of Saadh jan is unbeatable. Here is how battle ensues and why Gursikhs are unbeatable in this battle:

1) These Gursikhs wear the armour of humility on their bodies - ਸੰਨਾਹੰ ਤਨਿ ਨਿੰਮ੍ਰਤਾਹ ॥.

3) Their shield that they wear on their hands or hold with their hands is ਗੁਰ ਸਬਦ ਕਰ ਚਰਮਣਹ i.e. the Shabad of Guru i.e. Gurmantra of Guru. This is their ਕਰ ਚਰਮਣਹ i.e. shield in their hands.

4) Finding the path of Vaheguru is for them riding horses and elephants in the battlefield. How do Gursikhs find the path of Vaheguru? We will refer to another shabad for this question - ਰਾਮ ਰਾਮ ਬੋਲਿ ਬੋਲਿ ਖੋਜਤੇ ਬਡਭਾਗੀ ॥ By japping Naam again and again, they find Vaheguru.

5) In the spiritual battlefield that goes on inside, they walk around without fear and attack the enemies by doing kirtan of Gopal.

6) They win over the whole world, by bringing under control the five powerful thiefs i.e. Kaam, Krodh, Lobh, Moh and Ahankaar.

I was thinking of this shabad yesterday, Saadh sangat jeeo, and I found something interesting. Please ponder upon the second pankiti that goes as follows:

ਆਵਧਹ ਗੁਣ ਗੋਬਿੰਦ ਰਮਣੰ ਓਟ ਗੁਰ ਸਬਦ ਕਰ ਚਰਮਣਹ ॥

In this pankiti Siri Guru jee is stating that while battling Vikaars, the weapons are ਗੁਣ ਗੋਬਿੰਦ ਰਮਣੰ i.e. Getting absorbed in Gurbani paath/Kirtan whereas the protection/shield against attacks of Vikaars is Gur-Shabad i.e. Naam Gurmantra. This provides us the guidance that when we are faced with attacks from Kaam, Krodh and other bikaars, we should immediately take up Naam Gurmantr and when we want to do a pre-emptive strike against these vikaars, then get absorbed in Gurbani.

A Gursikh of Bhai Sahib jee's times and whom I think to be one of the most chardi kala Gursikh of present times, explained to me that Puratan Ranglay Sajjans of Bhai Sahib's times used to tell that good spiritual avastha is considered to be when a Gursikh japps Naam with Rasna, inside that Gursikh Gurbani paath too goes on in full force and when doing paath outwardly, Gurmat Naam goes on in full force inside. Such Gursikhs are fortunate and have kirpa of Guru Sahib who can do both at the same time. I recalled that Bhai Sahib has written about the same thing in several of his books.

Another thing Bapu jee told me was that while a Gursikh should use rasna to do paath everyday but some paath should be done purely in surthee. This makes the surtee balvaan (strong). So if you are doing more than one Siri Sukhmani Sahib, it would be a good idea to do at least one of the Siri Sukhmani Sahib or few Siri Jap jee Sahibs a day, purely in surthee. This was the advice of Bhai Atma Singh Panjokhra Sahib.

ਓਟ ਗੁਰ ਸਬਦ ਕਰ ਚਰਮਣਹ
Take the shelter of Gur Shabad which is our shield against these vikaars.
Part of the first pankiti also tells us of nimrata being our body armour
ਸੰਨਾਹੰ ਤਨਿ ਨਿੰਮ੍ਰਤਾਹ
So our shield and body armour is Gurbani and humility which would neutralise the brunt of any attack

ਆਵਧਹ ਗੁਣ ਗੋਬਿੰਦ ਰਮਣੰ
Then if any vikaar were to penetrate our defences, they would be defeated by the weapon of Gurmantar Naam/Naam Khanda

Also, great advice to make surthee balvaan by doing some paath in surthee.
I think also we should daily jap naam in pure surthee to keep our Naam Khanda strong and sharp. This would be ideal to do during worldly affairs such as at work and in some duties of grist.
Bhul chuk maaf karna sangat jee